The ratio of girls to the boys in a school is 4 : 5. If the number of girls is 1500, find the number of boys in that school. Also, find the total number of children in that school.

Given:

The ratio of boys and girls in a school 4 : 5

Number of girls = 1500

To find: Here we have to find the number of boys and the total number of children in that school.

Solution:

Given that, ratio of boys and girls in the school is 4 : 5.

Let the common factor be = $x$

So,

Number of boys = $4x$

Number of girls = $5x$

Also given that number of girls is 1500. Then,

$5x$ = $1500$

$x$ = $\frac{1500}{5}$

$x$ = 300  

Use this value of $x$ to calculate the number of boys:

Number of boys = $4x$

Number of boys = $4\ \times\ 300$

Number of boys = 1200

The total number of students in the school is:

Number of boys $+$ Number of girls

= 1200 $+$ 1500

= 2700

So, 

Number of boys = 1200

Total number of children = 2700